The present invention relates generally to an exposure apparatus used to fabricate various device including semiconductor devices and liquid crystal display devices, and more particularly to an immersion type exposure apparatus for immersing the part of the projection optical system and the surface of the object in the liquid and exposing object through the liquid.
Along with the recent demands on minute fabrication, the improvement of resolution of the projection exposure apparatus has been increasingly required. The higher numerical aperture (“NA”) of the projection optical system is effective to the improvement of the resolution, and the immersion exposure attracted people's attentions as one means that satisfies this demand. The immersion exposure exposes the object through the liquid that fills between the final surface of the projection optical system and the object, and promotes the higher numerical aperture and the resolution by using a medium that has a refractive index higher than the air's refractive index as the fluid. The immersion exposure proposes arranging a nozzle that supplies and recovers the liquid at near the final lens of the projection optical system, immerses the limited area between the final surface of the projection optical system and the object with the liquid, and circulates this. These nozzles are typically arranged along the outer diameter of the final lens of the projection optical system. See, for example, International Publication No. WO99/49504.
However, the prior art should form a channel that has the distance corresponding to the outer diameter of the final lens between the final lens and the object because the nozzle is arranged along the outer diameter of the final lens. The distance becomes long according to the enlargement of the outer diameter of the lens and the recent higher NA. Thereby, uniformly controlling the temperature and pressure of the liquid that flows into the channel has become difficult. The irregularity of the temperature and pressure of the liquid negatively affects the exposure light that passes there, and the high-quality exposure is difficult. On the other hand, throughput decreases if time is spent on the control of the temperature and pressure of the liquid. Moreover, the organic matters as the resist begins to melt from the object to the liquid, and the calcium fluoride (CaF2) used widely as a material of the final lens similarly melts easily to the liquid. Therefore, the contamination of the liquid increases though the flesh liquid always circulates when the channel between the final lens and the object is long, and the deterioration and irregularity of transmittance are caused. The organic matter in the liquid adheres to the surface of the final lens, and the deterioration and irregularity of transmittance are caused. The deterioration and irregularity of transmittance negatively affects the exposure light that passes there, and the high-quality exposure becomes difficult.